WO2014067716A1

WO2014067716A1 - Led light system

Info

Publication number: WO2014067716A1
Application number: PCT/EP2013/069885
Authority: WO
Inventors: Jörg FRISCHEISEN; Stefan Lange
Original assignee: Osram Gmbh
Priority date: 2012-10-30
Filing date: 2013-09-24
Publication date: 2014-05-08
Also published as: US9431587B2; DE102012219873A1; US20150311406A1

Abstract

An LED light system having colour locus stabilization on the basis of semiconductor components has at least two different types of LED semiconductor components, wherein the radiation of a first type of semiconductor components is at least partly converted by a first means for conversion. The radiation of the second type of semiconductor components has a longer wavelength than that of the first semiconductor component, wherein the second semiconductor components are arranged such that the radiation thereof is substantially not absorbed by a phosphor. For colour locus stabilization, a second means for conversion is disposed in front of the first semiconductor component, the conversion behaviour of said second means for conversion being temperature-dependent.

Description

description

LED LIGHT SYSTEM

TECHNICAL FIELD The invention relates to a lighting system with color space stabilization according to the preamble of claim 1. Such lighting systems are particularly suitable for general lighting.

State of the art

From US Pat. No. 6,234,648, a lighting system is known in which blue LEDs and red LEDs are used together with a phosphor, which ^converts the radiation of the blue LED into green

Radiation transforms.

From DE 10 2010 034 913 the use of materials for LEDs is known whose refractive index is temperature-dependent. The definitions used here for operating tempera ^¬ ture, refractive index and change in refractive index as a thermal mo-optic coefficient dn / dT should look for the following application.

Presentation of the invention

The object of the present invention is to provide a light system whose color impression remains as stable as possible at different temperatures. The differing ^¬ chen temperatures often result in the start-up phase of operation or in different environments. Preference is given to a white color impression, but a colored color impression is not excluded.

This object is achieved by the characterizing features of claim 1. Particularly advantageous embodiments can be found in the dependent claims.

A light system with color locus stabilization on the basis of semiconductor components has according to the invention at least two different types of semiconductor components, wherein the radiation of a first type of semiconductor components is at least partially converted by a first means for conversion. The radiation of the second type of Halbleiterbau ^¬ elements is longer wavelength than that of the first Halbleiterbau- elements, wherein the second semiconductor devices are angeord ^¬ net, that their radiation is not absorbed by a phosphor substantially. For color locus stabilization, a second means for Kon ^¬ version is connected upstream of the first semiconductor device whose conversion behavior is temperature-dependent.

In particular, a lighting system based on a first conversion LED and a second single-color LED, in particular a red LED, is provided.

The invention relates in detail to lighting systems such as LED lamps or LED lights, which are based on the partial conversion of light from mostly blue or UV LEDs by phosphor combined with other LEDs of larger wavelengths, eg red emitting, so that a total of certain, mostly white, color impression arises. The partial conversion can either take place close to the chip, or one can use a remote solution in which the LEDs are spatially separated from the phosphor. In this case, the phosphor in a matrix such as plastic / polymer, glass, silicone, or the like. eg be attached as a kind Kup ^¬ pel or plate over the LEDs.

Since the efficiency of blue, generally InGaN-based, and longer-wavelength second LEDs, mostly red LEDs, which are generally based on InGaAlP, varies differently with increasing temperature, increasing the temperature will shift the color location. Usually The light system emits more red light at room temperature or shortly after switching on than at operating conditions (ie at a higher temperature than room temperature), if no countermeasures are taken.

The peak emission of the shorter wavelength first LED is generally in a range of 350 to 460 nm, the peak emission of the longer wavelength second LED is generally at least 500 nm, often at least 570 nm.

There are various approaches for compensating the chromaticity shift:

1. Active control of the currents for first, in particular blue, and second, in particular red, LEDs depending on the temperature. This variant has the disadvantage that the necessary for the regulation electronic driver is very expensive and therefore expensive. 2. Use of suitable phosphors or phosphor mixtures so that the spectrum of the converted first, advantageously blue, LEDs leads to a partial compensation of the color location shift. In this case, one can make use of the fact that, for example, shifts the peak wavelength of the blue LEDs with temperature in a direction and at one ^¬ chen phosphors or phosphor blends is accompanied by a change in their emission spectra or the relative absorption or excitability. However, this variant can not compensate the color locus shift well enough in the case of a group of two LEDs emitting blue and red. 3. The passive optical element with a litter material, such as glass ^¬ particle, are attached to the second, red LED in a matrix, for example silicone. Here, the temperature-dependent refractive index of silicone is used, which becomes smaller with increasing temperature. The difference is about 0.035 between room temperature and 125 ° C. In contrast, the refractive index of glass is almost constant in this temperature range. If one adapts the used scattering materials from the refractive index so that under operating conditions the refractive index of Scattering material and matrix is almost equal, then the scattering effect is minimal in operating conditions, while at room temperature, a greater refractive index difference and thus a higher scattering effect is present. The passive optical element thus leads to scattering losses for the light of the second, red LEDs occurring at room temperature, while under operating conditions the light from the red LEDs is radiated largely undisturbed. This reduces the color locus shift with temperature. The effect can be enhanced by additional absorber materials in the matrix. This variant has the disadvantage of losing a portion of the emitted light even in operating conditions since the op ^¬ tables element is not transparent perfect. This will be destroyed at operating conditions and especially at lower temperatures ren light and thus reduces the efficiency and there is need for more red LEDs and thus the cost it ^¬ increased.

4. Use of a wavelength-dependent absorber material or filter. One uses the effect that the emission of the red LEDs shifts with increasing temperature to longer wavelengths. It is therefore a filter with a steep transmission curve can be used so that at room temperature part of the emission is absorbed, while under operating conditions, the light of the red LEDs is transmitted as freely as possible. Disadvantage of this variant is also that light is deliberately destroyed and ty ^¬ pically, even with operating conditions, a certain residual loss is present.

The invention provides as a solution to the problem above all the use of an additional temperature-dependent converter element, which is at least the first group of LEDs pre ^¬ switched and emitted in a spectral range, which is in Wellenlängenbereicht the second group of Halbleitererbauele ^¬ ments. The emission preferably differs at least one of the converter material contained in the temperature-dependent converter element not or only slightly from the emission of the second semiconductor device. This can be achieved by playing the appropriate tuning of the respective peak or dominant wave lengths of both emission spectra at ^¬. In particular, both Emis ^¬ sion spectra can for example be in the red spectral range.

This element consists of one or more Leucht ^¬ materials in a suitable matrix. At least one luminescent substance which emits secondary radiation which lies in the region of the emission of the second semiconductor element and matrix are selected so that the difference of their refractive indices at low temperatures, eg at room temperature or shortly after switching on the lamp, is very high is small, while the difference in their refractive indices at higher Tem ^¬ temperatures, for example at operating conditions of the lamp is larger. As a result, the light, which penetrates the temperature-dependent converter element, hardly scattered at low temperatures and the optical path length is relatively low, so that little light of the first LED, usually blue, can be absorbed by the phosphor and converted. At higher tempera tures ^¬ the light is scattered, the optical path length becomes greater and it will absorb more blue light and converted. Overall, the emitting in the spectral range of the second semiconductor element, in particular for

Example red-emitting phosphor of temperaturabhängi ^¬ gen converter element at room temperature, so almost "un ^¬ visible", ie it is not noticeable, while changing at a higher temperature, the refractive index of the matrix and therefore the scattering and absorption of light by the temperature-dependent converter element is greater ,

Possibly. For example, the element may also comprise an inorganic filler. According to one embodiment, the inorganic filler may comprise a glass, quartz, silica gel, SiO 2 particles, in particular In particular, spherical Si0 ₂ particles, a borosilicate glass or a combination thereof include or consist of. For example, Si0 ₂ particles have an index of refraction at room temperature of 1.46, glass of 1.45 to 2.14, borosilicate glass of 1.50 to 1.55.

According to a further embodiment, the filler comprises or consists of a silicate, a ceramic or an aluminum oxide, for example corundum.

According to a further embodiment, the matrix material may comprise or consist of a silicone, an epoxy resin, an acrylic resin, a polyurethane, a polycarbonate or a combination thereof. The matrix material may also comprise or consist of a mixture of different plastics and / or silicones. The matrix material may in particular comprise or consist of a silicone, a methyl-substituted silicone, for example poly (dimethylsiloxane) and / or polymethylphenylsiloxane, a cyclohexyl-substituted silicone, for example poly (dicyclohexyl) siloxane, or a combination thereof.

For example, an epoxy resin or an acrylic resin may include 1:48 to 1:53 a refractive index at room temperature, 1.46 to 1.60, in particular ^¬ sondere. A polycarbonate generally has a higher refractive index, for example 1.55 to 1.65, in particular 1.58 to 1.60. A silicone has a refractive index of 1.40 to 1.54.

Particularly advantageously, the refractive index of the matrix Mate ^¬ rials is adjusted so that it is higher at room temperature than the refractive index of the filler, since often the thermo-optical coefficient of the matrix material is higher than the thermo-optical coefficient of the filler, and thus the

Refractive index of the matrix material decreases with increasing temperature faster in operation of the device than the Bre ^¬ deviation index of the filler. Silicone is suitable as the matrix material of the temperature-dependent converter element, for example, which is available in various variants with refractive indices between about 1.39 and 1.55. The refractive index of the silicone depends comparatively strongly on the temperature and decreases with increasing temperature. As the phosphor of the temperature-dependent converter element are all materials in question have a similar refractive index At low temperatures ^¬ Geren as the matrix material. The difference should not be greater than 10%, better not more than 5%.

In principle, all phosphors come into question, which absorb the light of the blue LEDs and then emit secondarily at a longer wavelength. Above all, red emitting phosphors are interesting, but also orange or green emitting phosphors. In the former case more blue light is converted into red light than at low temperatures, at higher temperatures ^¬ Tempe. Thus, the color locus shift in a first and second LED system can be improved and stabilized so there is less color locus shift between power up and operating conditions. In principle, it is also possible to use, if appropriate, phosphors which do not emit in the red spectral range. This also makes it possible to influence the color location as a function of the temperature.

This applies in particular if the first LED (or group of LEDs) uses a UV-emitting LED. It is then possible, for example, to use a phosphor which absorbs in the UV range and emits in the blue spectral range. Examples of suitable phosphor are luminescent materials from the basic type BAM or SCAP as they are be ^¬ known in principle.

In this case, you can attach this blue-emitting phosphor over a UV LED and thus generate more or less additional blue light depending on the temperature, the on the other hand can be further converted via a yellow, green or red phosphor.

The refractive index of a silicone depends in particular on the organic substituents R ¹ , R ² and R ³ on the silicon atom and on the degree of branching of the silicone. Terminal groups of the silicone can be with R ¹ R ² R ³ SIOI / 2, linear groups with R ¹ R ² Si0 _2/2 and branching groups R ¹ SI03 / 2 be ^¬ write. R ¹ and / or R ² and / or R ³ may be independently selected on each silicon atom. R ¹ , R ² and R ³ are selected from a variety of organic substituents having a different number of carbon atoms. The organic substituents may be in any proportion to one another in a silicone. As a rule, a substituent has 1 to 12, in particular 1 to 8, carbon atoms. For example, R ¹ , R ² and R ^{3 are selected} from methyl, ethyl, cyclohexyl or phenyl, in particular methyl and phenyl. Organic substituent having many carbon atoms increase the refractive index, as a rule, while smaller substituent ^¬ th result in a lower refractive index. For example, a silicone that is rich in methyl groups may have a low refractive index, for example from 1.40 to 1.44. On the other hand, a silicone which is rich in phenyl groups or cyclohexyl groups, for example, can have a higher refractive index.

In general, suitable material systems for the temperature-dependent phosphor are, for example, K ₂ SiF 6: Mn, CaF 2: Eu, SrF 2: Eu. In addition to the phosphor, additional scattering materials with a suitable refractive index can be added. Various embodiments are conceivable for this basic concept. In the case of near-chip conversion of the first, blue LEDs into, for example, green or yellow or red light, the invention can be realized as follows: The temperature-dependent conversion element can be connected upstream of each blue LED, or even only part of the blue LEDs.

The element can also be connected in series to all blue LEDs.

The element can be connected upstream of first, blue, LEDs and second, red LEDs. In this case, the red light of the LEDs is only slightly more scattered under operating conditions, but hardly absorbed.

The temperature-dependent conversion element can have an off ^¬ guide die in direct contact with the corresponding LEDs, in a second embodiment it may also be designed as a remote element, such as a plate or dome over the LEDs. It then has no direct contact with the LEDs.

Besides, the combinations of these embodiments are also possible when converting the blue LEDs into e.g. green / yellow / red light is not about chip-to-chip conversion, but about spaced conversion. If both conversion layers are designed as spaced apart, in principle different embodiments are possible for the sequence of the remote elements, in addition the elements can optionally be mounted over all the LEDs or only over a part of the LEDs.

For the introduction of the phosphors in the temperature-dependent conversion element many established Konversionstechni ^¬ ken come into consideration, for example, is by means of sieve ^¬ printing, knife coating or produced by spraying tablets made of phosphor and a matrix material or Volumenver- cast, sedimentation, or electrophoretic deposition. In addition, manufacturing methods such as injection molding and extrusion can be used.

The scattering effect can be increased even more, in which one

Add your scattering materials with a suitable refractive index. The conversion effect in the temperature-dependent converter element can be enhanced by adding further phosphors. In particular, these are ^{Leuchtstof ¬} fe, which are either very coarse or very fine-grained. Thus phosphors having a d50 of at least 10 are, in particular on the one hand meant ym, on the other hand, phosphors having a d50 less than 200 nm. Such additives are, however inte ^¬ esting, because in this case their scattering effect is relatively small and thus the effect of the solution according to the invention even at low Temperatures are hardly affected. Therefore, under these circumstances, it is also possible to use phosphors whose refractive index differs from that of the matrix. Very fine grain phosphors may in particular quantum ^¬ points, so-called. Quantum dots are used, eg in the form of colloidal quantum dots. Suitable materials for

Quantum dots are, for example, semiconductor materials from the III-V, II-VI or I-III-VI2 groups, e.g. GaP, InP, ZnS, ZnSe, ZnTe, CdS or CdSe. To improve the properties (e.g., optical properties, stability, solubility), the quantum dots may be formed as a core / shell structure or contain ligands.

When using a temperature-dependent conversion element results in a number of advantages. It is intentionally not destroyed shortly after switching on or under operating conditions, as happens in other techniques mentioned above. According to the invention, only the lack of long wavelength, most red light at higher tempera tures ^¬ is by an additional red-conversion of the light of the first LED, usually is blue light, compensated. The color locus stabilization is thus achieved not by a destructive temperature-dependent absorption, but on the contrary by a constructive temperature-dependent Konver ^¬ sion. Therefore, there should be significant efficiency benefits. Since it is a passive optical element according to the invention, this solution is much cheaper compared to an active electronic control.

In addition, by the scattering effect of the temperature-dependent conversion element, the radiation properties of the

Improved lighting system, such as a more homogeneous In ^¬ tensitätsverteilung as a function of the radiation angle or a more homogeneous distribution of the color properties as a function of the radiation angle.

As phosphors which are geeig ^¬ net for use in the second means, in particular shell, orthosilicates, chloro silicates, nitridosilicates and derivatives thereof are proposed in particular:

(Ca, Sr) 8Mg (SiO 4) 4C 12: Eu 2+

(Sr, Ba, Lu) 2Si (0, N) 4: Eu2 +

(Sr, Ba, Ln) 2Si (0,) 4: Eu2 + with Ln selected from the Lanthanoids with the possibility of using more than one lanthanoid for Ln

(Sr, Ba) Si2N202: Eu2 +

(Y, Gd, b, Lu) 3 (Al, Ga) 5012: Ce3 +

(Ca, Sr, Ba) 2Si04: Eu2 +

(Sr, Ba, Ca, Mg) 2Si5N8: Eu2 +

(Sr, Ca) AlSiN3: Eu2 +

(Sr, Ca) S: Eu2 +

(Sr, Ba, Ca) 2 (Si, Al) 5 (N, 0) 8: Eu2 +

(Sr, Ba, Ca) 2Si5N8: Eu2 +

(Sr, Ba, Ca) 3Si05: Eu2 +

-SiA10N: Eu 2+

Ca (5-δ) Al (4-2δ) Si (8 + 2δ) 180: Eu2 +

Essential features of the invention in the form of a numbered list are:

1. Light system based on at least a first and ei ^¬ ner second groups of solid-state light sources, wherein a first means for at least partial conversion of the radiation of at least a first group, this group or any member of this group or at least a part of this first group is upstream, wherein the first means ^comprises a phosphor containing layer as Kon ^¬ version means comprising at least a portion of the converted primary radiation of the first group into secondary radiation with a longer wavelength, the two ^¬ th group radiation of longer wavelength than that of the ers ^¬ th group emitted, characterized in that a second means for at least partial conversion of the primary radiation of the first group is present which is at least in front of a part of the first group, this means showing a temperature dependence of the Kon ^¬ version, which is based on a different temperature dependence of the refractive index of a phosphor and ei ^¬ ner embedding the phosphor matrix, said phosphor and matrix are selected such that at Raumtem ^¬ temperature the difference in refractive index is small and at operating temperature, the difference in refractive index at least 1.5 times as great as at room temperature. Small means that the difference is more than 5%, in particular ^¬ sondere most 2%. In particular, a value of 3% has proven itself. Room temperature means a temperature of at most 20 ° C, operating temperature is a temperature ^¬ ture of at least 100 ° C. Group means at least one element, especially a plurality. Solid state light source means a chip, LED, laser diode, module with such a semiconductor device or the like.

Lighting system according to proposal 1, characterized in that the material of the matrix of the second agent of the type Sili ^¬ kon, whose refractive index decreases with increasing temperature. Lighting system according to proposal 2, characterized in that the phosphor of the second agent is a phosphor having a peak emission in the range 580 to 660 nm. Lighting system according to proposal 1, characterized in that the material of the matrix of the second agent is of the type Sili ^¬ kon, whose refractive index at room temperature has a value of n = 1.39 to 1.55. Lighting system according to proposal 1, characterized in that the phosphor of the second agent at room temperature is similar to the matrix, and differs from this at most by 3%. Lighting system according to proposal 1, characterized in that the first group emits primarily blue, with in particular a peak emission in the range 430 to 470 nm. Lighting system according to proposal 6, characterized in that the phosphor of the second agent has a peak emission in the red spectral range at 580-660 nm. Lighting system according to proposal 1, characterized in that the first group emits primarily UV, in particular ei ^¬ ner peak emission in the range 330 to 400 nm. Lighting system according to proposal 8, characterized in that the phosphor of the second agent has a peak emission in the blue spectral range at 430 to 470 nm. Lighting system according to proposal 1, characterized in that a phosphor of the second agent is selected from the group K2SiF6: Mn, CaF2: Eu, SrF2: Eu, alone or in combination. Lighting system according to proposal 1, characterized in that the second means also has scattering materials with appro priate ^¬ refractive index. Lighting system according to proposal 1, characterized in that the first means comprises a phosphor which partially converts the primary radiation of the first group into secondary radiation with a peak wavelength in the range 480 to 580 nm. Lighting system according to proposal 1, characterized in that the second means is also connected upstream of the second group or a part thereof. Lighting system according to proposal 1, characterized in that the radiation of both groups mixes to white, in particular ^¬ special with a color temperature in the range 2300 to 8000 K. Lighting system according to proposal 1, characterized in that the second means comprises a further converting phosphor whose scattering behavior is kept low, that the average diameter of the phosphor particles d50 is either at least 10 ym or Hoechsmann ^¬ least 200 nm. Lighting system according to proposal 1, characterized in that the phosphor of the second means has a mean diameter of the phosphor particles in the range d50 = 0.8 to 20 ym, preferably to 8 ym. Lighting system according to proposal 1, characterized in that at least the second means spaced from the Ers ^¬ th group is mounted on a dome. 18. Lighting system according to proposal 1, characterized in that the second group emits primary red, with insbeson ^¬ particular a peak emission in the range between 580 and 660 nm. These are preferably LEDs type InGaAlP.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in more detail below on the basis of several exemplary embodiments. The figures show:

Fig. 1 shows a lighting system according to the prior art;

Fig. 2 shows a second lighting system according to the prior art;

Figure 3 to 12 different embodiments of a novel lighting system.

Preferred embodiment of the invention

1 shows known to the configuration of an optical system 1 for white light to RGB base as per se, see for ^¬ play, US-B 7213 940. The light source comprises as a half ^¬ semiconductor component a first group or at least one blue LED 2 of the type InGaN with a peak emission wavelength of, for example, 450 nm. The array further contains as a second group or at least one red emitting LED 3. As a first conversion means of the first group, here the first LED 2, near the chip a yellow or green emitting first phosphor 4, such as YAG: Ce (yellow) or green SiA

10N, upstream. The system mixes to white (6), example ^¬, with a color temperature of 2600 K.

Optionally, a diffuser 5 is pre scarf ^¬ tet the whole module, for better homogenization.

Figure 2 shows another arrangement of a prior art light ^¬ system 1, again with the first (2) and second (3) LED as shown in Figure 1. Here, the first means for conversion beabstan- Det arranged by the first group on a dome 8, it is a so-called. Remote phosphor concept. The dome may also contain litter material.

Figure 3 shows in detail a first embodiment according to the invention, in the state at low temperature, in particular room temperature. The mode of operation of the first group of LEDs is explained, the second group is not shown here, it is similar to that in FIG. 1 or 2.

A representative of the first group here has a blue (b) emitting LED 2. As the first conversion means, a layer 14 of partially converting phosphor, similar to the first phosphor mentioned in FIG. 1 or 2, is applied directly to it. The converted radiation is labeled g. In addition, a white ^¬ tere second layer is connected upstream of the first means 10 as a second means, here it is applied directly to the first means. The second layer 10 comprises at least two components, namely a matrix of Si ^¬ Likon 11 and a phosphor 12 with a strongly temperature-dependent refractive index represented in a highly schematic. Of the

Phosphor is especially K2SiF6: Mn. This has a Bre ^¬ index at room temperature of about 1.4 and is thus particularly well suited for interaction with silicone.

At a low temperature of typically 20 ° C., the difference in the refractive index between the matrix 11 and the second temperature-dependent phosphor 12 is relatively small, for example below 5%, specifically here about 3%. Therefore, the scattering and thus the optical path length of the light is very low. Thus, the rate of conversion of the blue primary radiation into red secondary radiation is so low that it does not play a significant technical role. Figure 4 shows the conditions of the first Ausführungsbei ^¬ game at high temperature, typically 80 to 180 ° C in the operating state. At this temperature, the difference in the refractive index between the second phosphor 12 and an embedded matrix 11 is significantly higher, for example three times as high as at room temperature. As a result, blue light from the LEDs of the first group is converted to red light (r) to a significant degree. As a result, the color locus shift compared to the initial phase immediately after the start, as described in FIG. 3, is at least partially compensated again.

Figure 5 shows a further exemplary embodiment schematically, wherein the first group consists of two LEDs 2, of which the own second means is each ^¬ upstream sixteenth

6a shows an embodiment in which a group of two blue LEDs 2 (first group) is a cross-Plätt ^¬ chen is preceded by 17 with the second agent. Each first LED 2 has the first conversion means 4 close to the chip.

6b shows an embodiment in which the second ^¬ tel With no separate platelets, but a casting 18, which not only sits before each of the blue LEDs 2 in the light path, but also laterally between the two LEDs. 2

FIG. 7a shows an exemplary embodiment analogous to FIG. 6a, in which the second means as a plate 20 extends not only via the first group, represented here by two blue LEDs 2, but also via the second group, represented by a red-emitting LED 3. Alternatively, according to FIG. 7b, the second means may again extend, as encapsulation 21, also to the intermediate spaces between the semiconductor elements 2, 2, 3. FIG. 8 shows a module in which the first and second groups of LEDs 2, 2, 3 are seated together on a substrate 25. The first group has chip near conversion means 4 as the first Means open, for conversion to yellow / green. The temperature-dependent second means 22 is introduced into or applied to a dome spanning all light sources.

FIG. 9 shows, as a light system, a white-emitting LED module in which the second means 30 is applied close to the chip directly to the LEDs 2 of the first group of light sources. First (2) and second (3) group are plotted together on a sub strate ^¬ 25th A dome 8 spans both groups together, this dome having the first conversion means 31. This arrangement is particularly suitable for com ^¬ pensation, as the first means 31 is not exposed to too much thermal stress, so a certain tempera ^¬ turempfindlichkeit the refractive index of the first phosphor can be accepted. Conversely, the temperature-sensitive second phosphor in the second means 30 is exposed to a maximum difference in temperature and can thus fully develop its regulating function.

FIG. 10 a shows a lighting system that is constructed similarly to FIG. 9, but here the temperature-dependent converter element extends as a plate 20 over both first LEDs 2.

Figure 10b shows a similar optical system, wherein the temperature-dependent converter element also Zvi ^¬ rule extends as a casting 21, the two blue LEDs. 2 Figure IIa shows a similar lighting system, but the plate 20 with the second means also extends over the LED 3 of the second group.

Figure IIb shows a similar lighting system, wherein the temperature-dependent converter element 21 also extends between the blue (2) and red (3) LEDs

FIG. 12 a shows a particularly preferred exemplary embodiment of an LED module which, similar to that described in FIG. is built. In contrast, blue (2) and red (3) LEDs are each mounted on the substrate 25 without phosphor. A first dome 88 spans over it, which contains the second means 89, that is to say the temperature-dependent converter element. Outside the first dome spans a second dome 90, which contains the first means 91, ie the temperaturunab ^¬ dependent phosphor which emits yellow or green. The first and second means may be reversed in order. Figure 12b shows another embodiment, figure 12a is similar, but the first and second means is each ^¬ weils placed only over a portion of LEDs, namely via the LEDs 2 of the first group.

Claims

Light system based on at least a first and a ^second group of solid-state light sources, wherein a first means for at least partial conversion of the radiation is upstream of at least a first group, this group or each representative of this group or at least a part of this first group, wherein the first means has a layer containing a phosphor as a ^conversion medium, which converts at least part of the primary radiation of the first group into secondary radiation with a longer wavelength, the ^second group emitting radiation of a longer wavelength than that of the ^first group, characterized in that a second means for at least partial conversion of the primary radiation of the first group is present, which is located in front of at least part of the first group, this means showing a temperature dependence of the ^conversion , which is based on a different temperature dependence of the refractive index of a phosphor and ^a matrix embedding the phosphor is based, the phosphor and matrix being chosen so that at room ^temperature the difference in the refractive index is small and at operating temperature the difference in the refractive index is at least 1.5 times as large as at room temperature.

Light system according to claim 1, characterized in that the material of the matrix of the second agent is of the ^silicon type, the refractive index of which decreases with increasing temperature. Light system according to claim 2, characterized in that the phosphor of the second means is a phosphor with a peak emission in the range 580 to 660 nm.

4. Light system according to claim 1, characterized in that the material of the matrix of the second agent is of the silicon ^type , the refractive index of which has a value of n = 1.39 to 1.55 at room temperature.

5. Light system according to claim 1, characterized in that the phosphor of the second agent at room temperature is similar to that of the matrix and differs from it by at most 3%.

6. Light system according to claim 1, characterized in that the first group emits primarily blue, in particular with a peak emission in the range 430 to 470 nm.

7. Light system according to claim 6, characterized in that the phosphor of the second agent has a peak emission in the red spectral range at 580 to 660 nm.

8. Light system according to claim 1, characterized in that the first group primarily emits UV, in particular with a ^peak emission in the range 330 to 400 nm.

9. Light system according to claim 8, characterized in that the phosphor of the second agent has a peak emission in the blue spectral range at 430 to 470 nm.

10. Light system according to claim 1, characterized in that a phosphor of the second agent is selected from the group K2SiF6:Mn, CaF2:Eu, SrF2:Eu, alone or in combination.

11. Light system according to claim 1, characterized in that the second means also has scattering materials with a ^suitable refractive index.

12. Light system according to claim 1, characterized in that the first means has a phosphor which partially converts the primary radiation of the first group into secondary radiation with a peak wavelength in the range 480 to 580 nm.

13. Light system according to claim 1, characterized in that the second means is also connected upstream of the second group or a part thereof.

14. Light system according to claim 1, characterized in that the radiation from both groups mixes to white, in ^particular with a color temperature in the range 2300 to 8000 K.

15. Light system according to claim 1, characterized in that the second means has a further converting phosphor, the scattering behavior of which is kept low in that the average diameter of the phosphor particles d50 is either at least 10 ym or at ^most 200 nm.

16. Light system according to claim 1, characterized in that the phosphor of the second agent has an average diameter of the phosphor particles in the range d50 = 0.8 to 20 ym, preferably up to 8 ym.

17. Lighting system according to claim 1, characterized in that at least the second means is mounted on a dome at a distance from the ^first group.